Treatment of hydrocarbon oils



Jan. 7, 1936. L.. DE FLoRl-:z

TREATMENT OF HYDROGARBON OILS Filed Apr'1l`27, 1935 INVENTOR LUIS DEFLOREZ www df M ATTORNEY Patented Jan. 7, 1936 I i f i UNITED sTATEsPATENT OFFICE 'rnEA'rMENT'oF mmRocAnnoN oILs Luis de Flor-ez, Pomtret,Conn., assigner to The Texas Company, New York, N. Y., a corporation ofDelaware Application April 21, 1933, serial No. 668,180 ve Claims. ,(01.19e-94) This invention relates to the treatment of `hyrelatively heavycondensate such, for exampla'as drocarbon oils, lsuch as those derivedfrom petrogas oil, while the gases liberated in the flashing leum, andmore particularly to the fractionation or weathering zone are treatedwith relatively of mixed hydrocarbon vapors such as those pro-v lightcondensate, such for example, oS Elf-heavy duced when hydrocarbon oilsare subjected to naphtha fraction withdrawn as 'a side stream 5 crackingto promote the formation of lower-boilfrom the fractionatlng zone. ingoils such as gasoline, naphtha, gas oil or In other embodiments of myinvention, howthe like. ever, the gases Withdrawn from the separating Anobject of my invention is to provide a andflashing Zones may be Combinedfor treat'- lo method of fractionating4v mixed hydrocarbon ment with asingle absorbent oil or may be treat-` 10 vapors containing constituentsof different boiled in separate stages with a. single absorbent oil,ying points for the recovery of a number of conwhich may be either ereletivelv heavy C0nden` stituents therefrom, whereby lightconstituents, Sete Such as gas oilor an intermediate condensuch forexample, as gasoline, may be separated sate such as a heavy nophthafraction.

l5 from heavier constituents as well as lower-boil- Where anintermediatefraction is employed for 15 ing constituents or gases and recovered in asutthe purpose of treating gases Withdrawn from the able and desirableform, 1 separating zone or the dashing zone or both, it is My inventionhas for further objects such adpreferably rst stripped, as for example,`by'treatditional improvements in operative advantages ing it With Steamin Suitable apparatus, before and results as may hereinafter be found toobtain. being contacted With the gases treated, for the 20 My inventioncontemplates delivering mixed purpose of removing 10W-boilingconstituents hydrocarbon vapors, such, 'for example, as a mix.` whichwould interfere with or reduce the eiliture of normally gaseousconstituents, gasoline oieney of the Subsequent treatment of the gases.constituents, gas-oil constituents, and interme- Myinvention `furthercontemplates the prodate constituents having boiling points lyingbevision of a combined cracking and fractionating 25 tween the boilingpoints of said gasoline and gast SYStem Wherein e petroleum oil s uoh,for examoil constituents, .to a fractionating zone wherein ple, 8Sreduced Crude or Bf geS oil moy be they are progressively cooled toeffect a. condensa,- cracked to eiect a conversion ofthe oil to lowertion of relatively high-boiling constituents, such, boiling ConstituentsSuch as gasoline and the for example, as gas-011 constituents, andpreferlike, the vapors being fractionated in the man- 30 ably also afraction comprising somewhat lowerner reoited hereinabove. boiling orintermediate constituents. 'In order that my invention maybe clearly Myinvention further contemplates the removal Set forthend understood, Inow describe; With of uncondensed vapors and gases Iromthe fracreferenceto the drawing accompanying and tionating zone, cooling the same toeiect a coni forming port of thiS Speoioation, various prey 35 densationof 10W .boiling Constituents such as ferred forms and manners in whichmy invention gasoline, and separating the condensate thereby may bepraotieed and embodied. In this draw-v obtaining from the remaininggases. The sepaing, rated condensate is then flashed to a loWer-pres-The Single gure iS d more or leSS diagramsure to remove gases containedtherein vand the matic elevational view of apparatus for effectgaseswithdrawn from the separating zone and ing the oraoking of o hydrocarbonoil and the also the gases withdrawn from lthe. npshmg or fractionationof the `resultant vapors in accordweathering zone are vtreated withabsorbent oil ance With mypresent invention. to remove normally liquidconstituents which may Referring 110W to the drawing. mixed hydro--l 4"be present thereininvapor form. I carbon vapors under a superatmosphericpres- Preferably the treatment of the gases removed sure or for examplefrom to 200 pounds per from the separating and flashing or weatheringSquare inch, are Supplied from a Source thereof, zones is carried out bymeans of 'condensate or such, for example, aS e' primary freotionatingcondensates. separated from the vapors in the tower or still l, by meansof a vapor-transfer 50 fractionating zone, and the venrichedcondensateline 2 having a valve 3 to a fraetionating tower 50 or condensates aftertreatment of the gases is or l, the interior of which is provided withplates are returned to the fractionating zone as reflux. or vtrays 5.0isuitable design; The plates or trays In the preferred form of myinvention, the gases 5 may comprise the conventional bells and traysremoved from theA separating zone are treated commonly employed infractionating vapor mixsubstantially without reduction of pressure withtures or any other gas-and-liquid-contact ap- 55 paratus suitable forthe fractionation oi' such mixtures.

By means oi' cool reflux oil introduced to the fractionating tower 4through conduits 6, 1, 1' or any of these, or by means of coolingeiected in any other manner, the vapors passing through thefractionating tower 4 are subjected to progressive cooling andcondensation while being maintained meanwhile under a suitablesuperatmospheric pressure of, for example from 50 to 200 pounds persquare inch, to such extent as to remove higher boiling constituents,such as gas oil, and where desired, a fraction comprising intermediateconstituents such as naphtha, leaving uncondensed the vapors orrelatively low 4boiling constituents such as light naphtha or gasoline.The latter, together with fixed gases and vapors of constituents lighterthan are desired to be included in the iinished gasoline, escape fromthe top of the Iractionating tower 4 through a vapor line 6 having avalve 9 and leading to a condenser I 6. i

The relatively high-boiling constituents removed from the vaporsentering the tower 4 collect in the bottom of the latter, from whichthey may be withdrawn through a conduit I2 having a valve I3 or aconduit I4 having a valve I5, while intermediate or heavy naphthaconstituents may be withdrawn as a side stream from a trap-out tray I6located at a suitable point in the tower 4 through the conduit I1 havinga valve I 3. The intermediate fraction thus withdrawn from the trap-outtray I6 may be passed through the conduit I6 having a valve 20 to astripper 22 which is provided with a steam inlet 23 as well as plates ortrays 24. By contact with the steam within the stripper 22, suchlow-boiling constituents as may be present in the intermediate fractionwithdrawn from the trap-out tray I6 are volatilized and may be returnedthrough a vapor line 26 to the fractionating tower 4 while the strippedintermediate condensate passes from the bottom of the stripper 22through a line 26 leading to a cooler 21.

Where the intermediate condensate withdrawn'from the trap-out tray I6does not require stripping, as for example, when it -is withdrawn merelyi'or the purpose o! providing a reux cooling effect in the fractionatingtower 4, the side stream withdrawn lfrom the trap-out tray I6 may beby-passed around the stripper 22 through a by-pass line 26 having avalve 29 and communicating with the conduits I1 and 26.

In the condenser I0 the vapors and gases leaving the top of thefractionating tower 4 are cooled by indirect contact with water,preferably to a substantially atmospheric temperature, thereby effectingthe condensation ot low-boiling constituents such as gasoline, and themixture oi' condensed and uncondensed hydrocarbons passes through aconduit 3| to a separator 32, the upper portion of which ymay lbeprovided with a plurality of separating bales 33, for the purpose ofassisting in the separation of the gases and the gasoline distillate.The separated gasesV pass from the separator 32 through a gas line 34having a valve 36 to a scrubber or absorber 36, the interior of which isprovided with plates or trays 31 or other suitablegas-and-liquid-contact means.

The gases thus entering in the scrubber 36, which normally contain somegasoline vapors, are treated for the removal of the latter by means ofabsorbent oil introduced to the upper portion o! the scrubber 36 througha conduit 36.

In the preferred instance, gas oil removed from the bottom of theiractionating tower 4 through the conduit I4 is delivered through theconduit 38 to the scrubber 36, after ilrst passing through a cooler 33wherein it is cooled to substantially l atmospheric temperature byindirect contact with water or otherwise.

The gases entering the base of the absorber 36 and passing upwardlytherethrough under a pressure upward oi' 30 pounds per square inch, 10are scrubbed in countercurrent fashion by means of the absorbent oilentering the upper portion of the absorber 36 through the conduit 38 andare thereby stripped of their content of vapors cf gasoline or othernormally liquid constituents ll and leave the upper portion of theabsorber 36 in substantially dry condition through a conduit 4I having avalve 42 and communicating with a gas main 42. The enriched absorbentoil reaching the bottom of the absorber 36 is withdrawn N through aconduit 44 having a valve 46 and a pump 46. By means o! the pump 46 theenriched condensate is returned either to the top of the distillationvessel I, through a branch conduit 41 having a valve 46 andcommunicating with I6 the top of the vessel I, or through a conduit 60having a valve 5I and branch conduits 62 or 63 to either or both of theinlets 1 and 1', respectively, in the fractionating tower 4. In thepreferred instance, the enriched gas oil from the l0 bottom oi' thefractionating tower 36 is returned in part to the top oi the primaryfractionating tower I and in part through the conduits 44, 60, 53, and1' to an intermediate level in the fractionating tower 4, a valve 64 inthe conduit 62 u being closed for the purpose of preventing flow of thisoil into the top of the fractionating tower 4. 'I'he condensatecollected in the bottom of the separator 32 under a pressure only alittle below that obtaining in the upper portion of the tower 0 4, andconsisting oi' raw gasoline containing undesirable light or gaseousconstituents dissolved therein, is wholly or in part withdrawn from theseparator 32 through a pipe 60 having a pressure-reducing valve 6I andflashed into the in- 45 terior of a weathering drum 62 maintained at apressure substantially below that obtaining in the separator 32, forexample, a pressure of from 1 to 15 poundsper square inch. The drum 62may be provided with a coil 63 for steam or other 50 heating iluid forthe purpose of assisting in the removal of the gases or otherundesirable light constituents from the gasoline, and also with bail'les64 for the purpose of assisting in the separation oi' gases andgasoline. 55 By means ofthe pressure reduction incident to the flashingof the gasoline from the separator 32, which may be assisted asaforesaid by heat supplied from the coil 63, raw gasoline entering 60the weathering drum 62 is freed from gases dissolved therein and theresultant weathered gasoline is withdrawn vfrom the bottom of theweathering drum 62 through a conduit 66 having a valve 66, while theliberated low-pressure gases 65 which, although small in amountinevitably contain a considerable proportion of vapors and lowboilingnormally liquid constituents pass from the top of the weathering drum 62through a conduit 61. By means of a branch conduit 66 hav- 70 ing avalve 63 and a compressor 10, these gases and vapors may be delivered tothe scrubber 36 for treatment together with the gases and vapors leavingthe separator 32, but in the preferred instance they are caused to passthrough a conduit 15 12 having avalve 13 to a low-pressure scrubber 14having interiorly-disposed plates or baflles 15 and supplied withabsorbent oil through a conduit 16 having a valve 11. In the'preferredinstance this absorbentoil comprises cooled intermediate oilwhich,\after having beeny withdrawn `from the trap-out tray I6 in thefractionating tower 4, has been stripped in the stripper 22 andy cooledin the cooler 21 and is thus in condition for .effecting the vremovalfrom the gases entering the scrubber 141of low-boiling normally liquidconstituents such as light gasoline ends.

'I'he scrubbed gases leave the scrubber 14 ina substantially drycondition through a conduit 18 having a'valve 18 and communicating withagas main 8|, while the enriched absorbent oil reaching the bottom of the`scrubber 14 is withdrawn therefrom through'a conduit 82 havingV `valves83 and 84 and a pump 85, by means of which the enriched absorbent oil isreturned to the fractionating tower 4. In reintroducing this oil intothe fractionating tower 4, the valves 54 and 5l as well as valves 86 and81 and the inletsl and'1',

respectively' may be manipulated so as to cause all ofA this oil' topass into the upper portion of the fractionating tower4-through'theinlet 1 or so as to divide the flow of absorbent oil between the inlets1and 1. Y

`By means of a branch l having a valve 3| and communicating withv theconduits 82 and 41 a portion ofthe enrichedcondensate oil from thescrubber v14 may also be returned to the top of the primaryfractionatingtower I to serve as reux therein", this procedure beingyespecially desirable where the treatment ofthe gases in the scrubbers v36 and 14 is carried out entirely by means of in'-l termediatecondensate withdrawnfrorn the trapout tray `I6 in the fractionatingtower 4'.

*As has beenindicated hereinabove. the preferred procedure is to passthe-relatively highpressure gases from the separator 32 to the scrubber36. and the relatively low-pressure Vgases from the weathering drum 62lto the lscrubber 14, the

scrubbing medium in the scrubber 36 comprising cooled gas oil with rawnfrom the bottom of the fractionating' tower 4 andthe scrubbing medium inthe absorber 14 comprising cooled and stripped intermediate Aoillwithdrawn from the trap-out tray I6. "Injthisinstance, the Venriched gasoil from the bottom of the'absorber' 36 is preferably returned in partto the primary Iractonating tower I and "in vpart through inlet 1 intothe iractionating tower 4 while the enriched inter.- mediate oil fromthe bottom of the absorber 14 is returned from thc inlet 1 to the top ofthe fractionating tower 4.

I may, however, accomplish the treatmentI of therelatively highlpressuregases in the absorber 36 and the relatively low-pressure gases in theabsorber 14 by means of separate portions of thev intermediate oilwithdrawn from the vtrap-'out tray I5. vIn-,thisv instancathe valve I5is closed anda portion "of, the oil leaving the cooler 21` is withdrawnthrough a branch conduit 94 having ajvalve 95 and communicating with theconduit 38 through vwhich this portionof the inter"-` mediate oilvpasses to the absorber 36..

itmay be noted at this point 4that there is ordinarilyl a suilicientpressure differential oetween theA vfractionating tower 4 and thescrubber 36 to permit voil Ywithdrawn from theformer to iiowto thelatter without vthe use of pumps, but pumps may be lprovided whereverthe pressure in tionating tower 4 to dispense with their use.

`from the main V43 to the main 8| `in suiiicient I may also,wheredesired, accomplish the treatment lof the gasesliberated from theseparator 32 and the weathering drum 52 entirely by means of gasoilwithdrawn from the bottom of the fractionating tower 4. AI provide aconduit 96 having a 5 valve 91 and communicating between the conduits 16and 38 for the purpose of vdelivering a portion ofthe gas oil from thecooler 39 ,tol the absorber 14 in addition to that portion which isnormally delivered through the conduit 38 to the scrubber 36. In thisinstance, the'valves 11 and 95 are closed and if a side stream iswithdrawn from the trap-out Vtray I6, it is ordinarily returned from thecooler 21 tothe fractionating tower 4 through a conduit IOI having avalve |02 and apump |03 and communicating with the conduit 6.'Alternatively, however, the `valve I8 may be closed and the reux oilsupplied through theconduit 6 to the fractionating tower 4 'may comprisecondensate removed from the separator 32 'through 20 a conduit |04having a valve |05 and a pump |06 and also communicating with the refluxconduit 6.

Where the gases vwithdrawn from the weathering drum 62 are passed bymeans ofthe compressor 10 and the conduitg68 into the absorber 25 36,the absorbent oil employed in the absorber 36 may Vcomprise intermediateoil from the trapout'tray I6 or gas -oil from the bottom ofthefractionating tower 4 as desired.` In thisasin other instances theenriched absorbent oil is returned 30 lin communications-with theprincipal plant gas main, whereas the main 8| may lead to nearby burnersemployed for heating associated cracking or distilling apparatus. In theinstance shown, I 45 have provided communication between thehighpressure main 43 and thelow-pressure main 8| through `a valvefI I0,which is preferably automatica-lly operated'to supplyhigh-pressure gasquantity to augment the volume of the low-pressure gases tor suchextentas may be desired for any purpose. i

While my 'inventionk may be 4utilized for the fractionationoi mixedhydrocarbon vapors of 55 various kinds and from various sources, it isesl pecially useful for the fractionation of vaporspro-yduced in thecracking of hydrocarbon oils and may advantageously Ybe combined withthe cracking of hydrocarbon oils. In the instance illustrated 60 in theaccompanying drawing', I have illustrated apparatus forcarrying out apreferred cracking process whichmay be advantageously combined with thefractionating methods set forthhereinabove. o5

According to this method of operation, an oil to be crackedI and therebyreduced `tolower-boiling oils and residue is introduced into the still Ifrom a source (not shownrthrough the con-` duit "I II whereinis'locatedavpump||2 and which 70 terminates in vtwo branches lI I3 and |I4ohavingvalves II'5 and ||6 respectively, leaclingto -differ-` ent points in thetower I. The interior of the tower I may be provided with baflles||1 anda tray orv plate II8V for-"the purpose of promoting 75 transfer line|22,

contact between the charging oil thus introduced and vapors introducedinto the tower I through a vapor line |24 leading from the reactionvessel or coking drum III. The latter is preferably supplied withcracked hydrocarbon vapors through a transfer line I!! from a heatingcoil III which in the' preferred instance illustrated receivesgas oilwithdrawn from the fractionatlng tower 4 through the conduit I2. A pump|24 is located in the conduit I2 for the Purpose of delivering this gasoil under a proper pressure to the coil |23.

In the preferred instance. the recycled gas oil withdrawn from thefractionating tower 4 is passed by, means of the pump |24 through theheating coil |23, wherein it is raised to a relatively high crackingtemperature of, for example, from 850 to i050 Il'. under a pressure offrom 200m 750 pounds per square inch. and the resultant cracked productsare discharged through the transfer line |22 into the coke drum orreaction vessel I2I where a separation of liquid and vapors occurs aswell as a continuation of the cracking inaugurated in the heating coilIII. The hot cracked vapors then pass through the vapor line |24 into.the tower Iwhere they are brought into contact with fresh charging oilintroduced by means of the pump Il! and a combined dephlegmating andvaporizing action takes place. Residual portions of the charging oiltogether with heavy condensate removed from the cracked vapors arewithdrawn from the bottom of the still I through a conduit III having avalve ISI and a pump [32 and communicating with the preferably throughan injector III. In this manner, combined residue and condensate fromthe bottom of the tower I may be brought to a cracking or cokingtemperature in the vessel I2I without the necessity of passing itthrough aV pipe coil, and the pipe coil |23 is provided with cleanstock, i. e., gas oil withdrawn from the bottom of the fractionatingtower 4, which may be carried to a very high cracking temperaturewithout excessive deposition of carbon therein.

While the cracking system set forth hereinabove represents a type ofprocess with whichl the fractionating methods of my present inventionmay advantageously be combined, it will be obvious to those skilled inthe art that my fractionating system may be applied to and used inconjunction with other tems.

Furthermore, while I have illustrated and described my invention withrespect to various illustrative examples and instances, it will beunderstood that my invention is not limited to ythe details of suchexempliflcations, but is broadly to be construed in accordance with thescope of the claims hereinafter made. l

I claim: v

l. The method of fractionally condensing mixed hydrocarbon vaporscontaining normally gaseous constituents, gasoline constituents, gasoilconstituents and intermediate constituents having boiling points lyingvbetween the boiling points of said gasoline and gas oil constituents,which comprises delivering said vapors to afractionaticn zone maintainedunder superatmospheric pressure wherein said vapors are progressivelycooled, separately removing a gas-oil fraction and an intermediatefraction at separate points in said fractionation zone. stripping saidintermediate fraction of gasoline constituents types of cracking sys-Apresent therein, removing uncondensed vapors and gases from saidfractionation zone, cooling them to condense gasoline constituents,separating the condensed gasoline from the remaining vapors and gases,scrubbing said vapors and gases I with a cooled portion of said gas-oilfraction to remove gasoline constituents therefrom and returning thethereby enriched gas oil to said fractionation zone. flashing thecondensed gasoline to a lower pressure to remove gases and undesirl ablelow-boiling constituents therefrom, scrubbing the thereby liberatedgases and vapors with said stripped intermediate fraction to removegasoline constituents therefrom and returning the thereby enrichedintermediate fraction to said l fractionation zone.

2. 'lhe method of fractionally condensing mixed hydrocarbon vaporscontaining normally gaseous constituents, gasoline constituents, andhigher boiling constituents, which comprises delivering said vapors to afractionation zone maintained under superatmospheric pressure whereinsaid vapors are progressively cooled, removing condensate comprisinghigher-boiling constituents from said fractionation zone, cooling saidcon- 25 densate, removing uncondensed vapors and gases zone, coolingthem to condense gasoline constituents, separating the condensedgasoline` from the remaining vapors and gases, scrubbing said vapors andgases with condensate from said fractionation zone to remove gasolineconstituents therefrom and returning the thereby enriched condensate tosaid fractionation zone, hashing the condensed gasoline to a lowerpressure to remove gases and undesirable low-boiling constituentstherefrom, removing condensate from said fractionating zone andstripping lighter constituents therefrom, scrubbing liberated from theconing the thereby enriched condensate to said fractionation zone.

3. The method oi fractionally condensing mixed hydrocabron vapors whichcomprises delivering said vapors to a fractionating zone maintainedunder superatmospheric pressure wherein said vapors are cooled toeii'ect a condensation of relatively high boiling constituents. removinguncondensed vapors from said high-pressure fractionation zone, coolingthem to condense relatively highv boiling constituents thereof,separating the condensate from the uncondensed gases and vapors,iiashing the condensate to a lower pressure to liberate gases and vaporsof lower boiling constituents thereof, scrubbing said uncondensed gasesand vapors first mentioned in a iirst scrubbing zone with a relativelyhigh boiling condensate absorbent oil removed from said fractionatingzone, scrubbing the gases and vapors liberated from said flashing stageina second scrubbing zone, separate from said first scrubbing zone, witha lower boiling condensate absorber oil removed from said fractionatingzone, and distilling rec5 sultant enriched absorber oil to separatedesired lighter fractions therefrom.

4. A method in accordance with claim 3 wherein said resultant enrichedabsorber oil is distilled by being introduced into said high pressurefrac- 7o tionating zone.

5. A method in accordance with claim 3 wherein the enriched absorber oilis removed from said nrst scrubbing lzone and is introduced into anintermediate point in said high pressure fraction- 7s ating zone andenriched absorber oil is removedfrom said second scrubbing zone and isreturned to an intermediate point in said high pressure fractionatingzone higher than the point to which the absorber oil from said firstscrubbing zone is returned.

6. The method of fractionally condensing mixed hydrocarbon vapors whichcomprises delivering said vapors to a fractionating zone maintainedunder superatmospheric pressure wherein said vapors are cooled to effecta condensation of relatively high-boiling constituents, removingfrom'said fractionating zone at least aportion of the condensate therebyobtained, stripping condensate so removed of relatively low-boilingconstituents and cooling the stripped condensate, removing uncondensedvapors from said fractionating zone and cooling them to effectcondensation of relatively low-boiling constituents, iiashing saidlow-boiling constituents to a lower pressure in a weathering zone toliberate gases contained therein, scrubbing said liberated gases at saidlower pressure, to remove vapors therefrom, with a portion of lsaidstripped and cooled relatively high-boiling condensate from saidfractionating zone, returning the thereby enriched condensate to saidfractionating zone, passing light gases and vapors remaining uncondensedafter the cooling of the ,uncondensed vapors removed from saidfractionating zone, to an absorbing zone oi' higher pressure than saidweathering zone and therein scrubbing said light gases and vapors withanother portion of the said stripped and cooled relatively high-boilingcondensate from said fractionating zone to remove desired constituentstherefrom, and returning the thereby enriched condensate to saidfractionating zone.

LUIS DE FLOREZ.

